Interruption of Late Visual Processing Causes an Attentional Blink

When the task is to detect two letter targets in a stream of non-letter (digit) distractors in rapid serial visual presentation, an attentional blink (AB; ie a deficit in the detection of a second target when it follows the first by approximately 100 – 500 ms) is often found to occur. In a series of four experiments with different numbers of display positions, with or without masking, we show that: (1) the AB, which occurs when all items are presented at the same display location, is reduced when targets and distractors are presented randomly dispersed over 4 or 9 adjacent locations; (2) the AB is reduced with the spatially distributed presentation even when backward masks are used in all possible stimulus locations and when the location of the next item in the sequence is predictable; (3) the AB is not due to either a location-specific forward or backward masking effect occurring at early levels in visual processing. We conclude that the AB is primarily a function of the interruption of late visual processing produced when the item following the first target occurs at the same location. It seems that, in order for the AB to occur, the item following the first target must be presented at the same location as that target so that it can serve both as a distractor and as a mask interrupting or interfering with late visual processing.